The present invention relates to a radio telephone in accordance with the preamble of the accompanying claim 1.
A radio telephone relates in this context to a wireless telephone whereby a radio communication can be arranged with a telecommunication network or another radio telephone. Hand-portable phone relates to a portable radio telephone, such as a mobile phone having a size and design suited for hand. The above definitions are based on publication No. TSK 19, "Matkaviestinsanasto--Vocabulary of Mobile Communications", published by Tekniikan sanastokeskus ry, Helsinki 1993.
The user interface of the radio telephone comprises at least a micro-phone, earpiece and keys for making a call and answering an incoming call. Additionally, particularly mobile phones comprise a display, whereby the user of the telephone can be given information e.g. of an incoming call.
To use a hand-portable phone often involves the problem that the telephone starts ringing in situations where the phone is beyond the reach of hands, for example in a pocket of a jacket lying on the car seat, in a bag, inside the breast pocket or in a place otherwise unhandy. Also, the telephone may start ringing in a situation when the answering is difficult in other respect, such as in bus, at a meeting or in church.
Attempts have been made to overcome the drawback by placing the entire radio telephone on a wrist strap, wherein the wrist telephone would be easy to carry along and, when the phone starts ringing, it would be close to the user and therefore easy to answer. For instance European patent application EP-602828 introduces a solution where the radio telephone is placed to a wrist-watch type case. Most parts, including the microphone, of the radio telephone are positioned in the body of the case, mainly an earpiece being placed in the cover part. When a call is initiated, the cover part is opened, wherein the distance between the microphone and the earpiece can be increased, which facilitates the use of the wrist telephone. The above mentioned publication mainly attempts to describe the mechanical implementation of a wrist telephone. Also U.S. Pat. No. 5,260,915 introduces a solution for mechanical realization of a wrist telephone. In practice, the prior art provides no means for packing the radio telephone to be compact in a manner that it would be sensible to place it on wrist, inasmuch as reasonable operation times are desired for the phone. Batteries for known radio telephones are still considerably larger and heavier than the entire wrist strap, wherein adapting the radio telephone on the wrist strap would require that a very small battery was used, which, however, would mean that the operation time of the wrist telephone would be very short at a single charge.
A further problem of the wrist telephone is how to implement the antenna. To place the antenna too close to the user's body, e.g. wound around the wrist strap, will deteriorate the properties of the antenna. This sets limitations on the operation distance of the wrist telephone from the base station or another radio telephone.
Yet another drawback of known wrist telephones is the fact that the efficiencies of the transmitters are so low that thermal problems are caused when the entire radio telephone is compactly packed on a wrist strap. The thermal load directed to the wrist telephone is further increased by the wrist of the user.